Modern fascias are usually made of uPVC as older wooden rafters, much like older soffits, tend to rot over time.
A fascia is a board that is attached to the exposed edges of the rafters.
Fascias are designed to seal the roof and protect your park home from the rain and wind as well as providing support for the guttering.
Soffits are protective coverings that are placed in the corner between the top of the wall and the roof of a building and are used as a sealant to protect the rafters from the weather.
Most modern soffits are made of uPVC as they are not susceptible to rot like wooden soffits are.